Antenna structure



Feb. 21, 1939. w. M. HAHNEMANN 1 ANTENNA STRUCTURE Filed March 26, 1956 132 V9]? 2 02 War/fer Max flafi/vemann I I fli'orney Patented Feb. 21, 1939 UNITED STATES PATENT OFFICE ANTENNA STRUCTURE Application March 26, 1936, Serial No. 70,992 In Germany March 26, 1935 2 Claims.

This invention relates to new and useful improvements in antenna structures, and particularly to improvements in non-directional antennas of the umbrella type having substantial 5 ground radiation.

In antennas of the above described type the diameter of the horizontal aerial is usually at least half a wave length. The antenna is preferably tuned to a multiple of one-half the operating wave length to insure that several current nodes be produced in the horizontal top conductors. Such antennas are particularly adapted for broadcasting because most of the high angle radiation is suppressed. It is much easier to fix the current and phase conditions of such umbrella type antennas than in other flat-topped antenna structures which comprise also vertical radiators in addition to horizontal radiators.

The invention proposes to improve these arrangements by the addition of means for elongating the top conductors. In this way upward radiation is still further decreased and the advantage space requirements will be reduced.

The invention will be understood from the following description and be particularly pointed out in the appended claims, reference being had to the accompanying drawing in which Fig. 1 is a diagrammatic elevation of an antenna structure embodying the invention by way of example, Fig. 2 is a diagram explaining the operation thereof.

The top conductors L are stretched horizontally and have downwardly extending branch conductors A connected below by coils V. Fitted toa vertical central conductor H is a coupling arrangement F for feeding the antenna structure in a well known manner.

If A denotes the operative wavelength then the height of the conductor H is equal to A/ 10 and the radius of the antenna structure equal to 0.4x. The dotted lines in Fig. 1 indicate the current distribution.

The coils V enable the horizontal conductor pieces L to be made shorter than would be otherwise feasible. 10

Due to the fact that the conductors A extend downward it will be much easier to adjust the coils V, if these are variable, than it would be if the coils were located directly in the conductors L. By adjusting the coils V the antenna struc- 15 ture can be suited to variations of the operative wavelength.

The radiation pattern is shown in Fig. 2.

What is claimed is:

1. A- non-directional antenna arrangement 20 with substantial ground radiation comprising an umbrella type antenna having top conductors of large horizontal dimensions and a central vertical radiator of a physical length equal to onetenth of the operating wave length, the spacial 5 length of each of said top conductors being at least equal to half the operating wave length, elongating chokes connected in said top conductors, the adjustment of said chokes being adapted to produce at least two current nodes on said conductors.

2. A system according to claim 1, wherein the elongating chokes are connected to downwardly extending branches of the top conductors.

WALTER MAX HAHNEMANN. 

